1. Technical Field of the Invention
The present invention relates to novel cosmetic/dermatological compositions for topical application, comprising water-in-oil emulsions containing a high content of hydroxy acids, for therapeutic treatment or care of the skin, nails or hair and/or of the scalp, and to the use of same, in particular for treating and/or preventing xerosis, ichthyosis, actinic keratosis and/or photoinduced cutaneous aging.
2. Description of the Prior Art
It is known to this art to employ hydroxy acids for preventing or reducing the dermatological signs of aging of the skin and/or of hair, which are due to factors that are intrinsic to aging or else to external factors, such as, especially, UV irradiation, air pollution, wind, cold, heat and cigarette smoke. These are also known active agents for treating dermatological afflictions related to a disorder of the keratinization of the skin, nails and/or hair, such as especially acne, xerosis, ichthyosis and actinic keratosis.
However, these hydroxy acids are difficult to formulate as an emulsion in cream or milk form. Indeed, when they are incorporated in a concentrated amount, the hydroxy acids render the formulation unstable and therefore difficult to commercially exploit.
In addition, these compounds present the disadvantage of causing tingling, itching or pulling sensations after their application, which can result in considerable discomfort. To avoid this discomfort, it has been considered to release the hydroxy acids slowly and gradually, while maintaining their effectiveness.
U.S. Pat. No. 4,772,592 describes a stable water-in-oil emulsion for topical application, for treating acne, which includes a C.sub.1 -C.sub.4 alkyl lactate, a silicone oil, a nonionic liquid emulsifier and C.sub.1 -C.sub.4 alkanol, these constituents being present in specific amounts. Volatile polar liquids such as the alkyl lactate and the alkanol are essential ingredients of this emulsion because, together with the silicone oil, they stabilize the emulsion. However, C.sub.1 -C.sub.4 alkanols present the disadvantage of being irritants to the skin or to the mucosae and hence of contributing to the aforesaid discomfort caused by the hydroxy acids.